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Erosion threatens Scroby windfarm stability

The continuing dredging of aggregate in close proximity to the Scroby wind turbines has brought about a considerable reduction to the Scroby Sandbank and loss of the seabed, to the extent that the wind turbines embedded nearby are now threatened with instability.

Three years ago the deeply entrenched power line taking the generated power from the Scroby turbines to the shore was stripped of protective cover due to sandpit demand brought about by the deepened dredged adjacent seabed area, leaving the cable dangling well above the eroded seabed leading to fracture, the repair of which was very expensive to replace. The power supply was lost until replacement resulted. This could and should have been heeded as a warning at that time. Further aggregate dredging should have been terminated then, but despite opposition to granting further dredging licences for the area, sea bed aggregate dredging continues, and each and every application for a licence to dredge is granted.

When gas lines were instituted for the North Sea platforms to the Bacton shore plant, they were deeply embedded in the ocean floor and covered with a thick layer of concrete. They have not suffered from exposure due to loss of the seabed. But then they are not close to the dredging site(s).

What at first seemed a good and relatively low cost idea and a possible solution for providing stability for the Scroby Windfarm turbines was proposed by EON and the MFA. Their proposition was to place polypropylene nets filled with rubber tyres placed at the base of the worst affected Scroby Wind Turbines to protect the base from further endangering erosion due to seabed lowering, indeed to capture more sand and gravel driven by the strong tides of the area.

In the past discarded rubber tyres have been tried as a means of sea defence at seaside resorts as a means of protecting the coastline from erosion. But there were misgivings then, in that the shoreline waves impacted the barrier by sand and gravel attack that would liberate shards of synthetic rubber which could choke the guts of fish. Furthermore, the components of such tyres are far from benign.

Using the rubber from tyres as an experimental dressing component for a road showed that leachate resulted after rain polluting the aquifer to an unacceptable level.

Mike King, Pat Gowen, Norma Gowen and many members of our Coastal and North Sea action Groups attended the Public Meeting held at the Caister-on-Sea Hotel on 10th September 2014, called by EON and the MFO, to hear from the horses mouth the plan intended, and to ask any questions and give views on using tyres in this way. An application Ref: MLA/2014/00273 was placed on the MFO website and and publicised in the local press. At first sight this application appeared quite reasonable and that it provided a degree of protection at minimal cost. It further reduced the land dumping of the mountain of discarded tyres that has been seen as contaminating the aquifer.

But a deeper study of the plan showed the practice not to be so benign as suggested at the meeting, and following further research into the issue has now led us to have grave concerns on the proposed practice.

The fishermen of the area expressed their concern through Paul Lines, the Secretary of the local fisherman’s organisation. He pointed out his own experience that polypropylene and synthetic rubber disintegrated on the seabed, and that the release of the tyres over large areas of the seabed would destroy the fishing ground.

MARINET responded to the MFO consultation with the following:

17 Heath Crescent,
Hellesdon,
Norwich,
Norfolk
NR6 6XD

FAO MMO – 16th September 2014

I respond to your press notice advertised application MLA/2014/00273.

Having attended, with other MARINET and North Sea Action Group members, the Caister Hall Hotel Public Meeting of 10th September 2014 and heard the advantageous claims made for placing nets of filled rubber tyres at the base of Scroby Wind Turbines to protect the base from endangering erosion due to seabed lowering, I have since researched the issue which has now led me to grave concerns on the proposed practice..

On the positive side:

(1) We are fully aware of the necessity to maintain the stability of the turbines to permit continued power generation, a vital factor in attempting
to lower the grave escalation of Carbon Dioxide. Three years ago the deeply embedded power line taking the generated power from the turbines to the shore was stripped of protective cover due to sandpit demand brought about by the deeply dredged adjacent seabed area, leaving the cable dangling well above the eroded seabed, the repair of which was very expensive to replace. The power supply was lost. This should have been heeded as a warning at that time. Further aggregate dredging should have been terminated then.

(2) We are also fully aware of the considerable loss of sand and shingle depth on the seabed and the reduction of the Scroby sandbank, also brought about by nearby offshore aggregate dredging, in the same way as this is stripping our beaches and dunes along the coastline. This main causative problem needs urgent rectification by the MMO recognising cause and effect and in doing so refusing to continue to grant further offshore aggregate licences at source as a preventative measure.

(3) We are further aware of the problems created by the growing discarded tyre problem, and the need to develop a safe and effective means to combat by environmentally acceptable recycling.

However, a serious negative side exists in prolonged tyre marine immersion, i.e. the introduction of toxins and carcinogens into the marine environment eco-system and food chain.

(a) Rubber tyres contain carcinogens, e.g. neoprene, butadiene, halogens, butyl rubber and organohalogens, which at the very least will act as pheromone disruptors, and at the worst as hormone disruptors,

(b) Rubber tyres also contain heavy metals, e.g. lead, cadmium, manganese, mercury and zinc, plus aluminium, all of which are toxic in the marine environment when exposed as the rubber tyres disintegrate.

Both (a) and (b) classes will be released as the tyres degrade in the aqueous medium, and further would be ingested by crustaceans, directly, or via barnacles, mussels, etc. then entering the food chain.

(c) The powerful tides of the area and the coarse mobile grit bombardment will create rubber shards that will be consumed by fish and so blocking the gut.

In the laboratory tyre leachate is often generated by inundating a tyre sample (plug, shred, chip, or crumb) with water. There are limitations when comparing the results of the reviewed laboratory studies as different makes of tyres were used and different compounds were measured; however the following general observations can be made about the tyre leachate generated in the laboratory:

it may be toxic to some fish species (e.g. rainbow trout but not minnow)

bacteria, invertebrates and green algae

levels of aluminium and manganese are likely to be elevated, especially where steel is exposed

levels of mercury and lead may be elevated; however most studies reported negligible levels

levels of zinc and organic compounds are likely to be dependent on individual circumstances as a wide range of levels have been reported in the studies reviewed
levels of other substances are likely to below United States Drinking Water Standards

levels of leachate compounds (metals and organic compounds) are likely to increase with time of inundation, increase proportionally with amount of tyre and decrease proportionally with size of tyre exposed to inundation.

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We noted that the parts of your presentation only briefly mentioning the negative factors suggested that these “should not result”. This assumption is not good enough. It is essential to know that they DO NOT and WILL NOT exist.

Thus, we object to the proposal as it stands, and suggest that a long term study of at least five years be instituted on a single turbine base so that removal and inspection is possible, in order to determine if such practice is environmentally acceptable in the long term future.